PRECISE MICROEARTHQUAKE HYPOCENTER DETERMINATION BY USING DETONATION SHOTS IN WELLS

抄録

Fractures in geothermal reservoirs can be located in three dimension by the microearthquakes observation as their hypocenter locations. However, microearthquake hypocenter location accuracy is depended on the underground seismic wave velocity structure which has a strong heterogeneity in the geothermal areas. Calibration tests using detonation shots in deep wells can compensate the heterogeneity. Field tests conducted in the Ogachi Hot Dry Rock (HDR) experiment showed that artificially created fractures were located accurately with 10 to 20 m errors by station correction values which were obtained by calibration tests at about 1,070 m depth.